Hes a virus, he impales the charging port to his victims to melt their brains out. He also uses it for Terra but I ain’t gonna give info about that one ask Evilish idk
He's probably not gonna do anything because he likes terra and data's her sister but data's still not gonna be happy about him existing anywhere near her
Basically data has trauma from an AI called the exotic creator breaching her systems and using her body to start a war. She was forced to watch him do horrific things while she was helpless to do anything about it for months.
The first thing miso did when she met him was breach her systems. Instant flashbacks.
If I remember right he chilled out afterwards, but data didn't.
Surprisingly she still ended up meeting S.A.P. (her boyfriend in the main timeline) though the love is mostly one sided since in the au she really creeps him out.